1. Field of the Invention
The present invention relates to a thin film transistor and a flat panel display including the same, and more particularly, to an organic electroluminescent display with a low contact resistance between source and drain electrodes and a semiconductor layer.
2. Description of the Related Art
Thin film transistors (TFTs) which are used in flat panel display, such as liquid crystalline display, organic electroluminescent display, inorganic electroluminescent display, and the like, act as switching devices that control the operation of each pixel, and as driving sources that operate the pixels.
A TFT includes a semiconductor layer that has source and drain regions doped with a highly concentrated impurity and a channel region formed therebetween, a gate electrode that is insulated from the semiconductor layer and disposed above the channel region, and source and drain electrodes that contact the source and drain regions, respectively.
Generally, the source and drain electrodes are formed of a low work function metal so that electric charges can move smoothly therein. However, when the low work function metal contacts the semiconductor layer, a high contact resistance results, and thus the characteristics of the device deteriorate and the power consumption is increased.
Recently, TFTs have become thin and flexible. In order to obtain such flexibility, conventional glass substrates have been replaced by plastic substrates.
Organic TFTs, which are being actively studied, include organic semiconductor layers that can be formed at low temperatures so that plastic substrates can be used. In this case, however, the contact resistance of a contact region between the source and drain electrodes and the semiconductor layer is high.